In D.Gray-Man, Road Kamelot constantly makes advances on Allen and is very...admired by her adoptive father, Sheril. But the revelation that Road is MUCH older than she looks (she's had the body of a twelve-year-old for over thirty-five years) makes these interactions creepier; not only is Allen half her age, but Sheril himself might be her junior. And technically, he's kind of her brother.
And, then, there are Sheryl's Ho Yay tendencies toward Tyki. If you know that the Noahs are the same age they are when they turned into a Noah, this makes it very Squicky.
A LOT of confusing details about Allen's past are starting to make sense now that the Fourteenth has revealed that they knew each other and were good friends. The question is how did Allen get younger than he was 35 years ago.